An apparent suicide bomber attacked an Ariana Grande concert as it ended Monday night, killing 22 people among a panicked crowd of young concertgoers, some still wearing the star’s trademark kitten ears and holding pink balloons as they fled.

Teenage screams filled the arena just after the explosion, which also killed the attacker and injured dozens.

The Islamic State terror group says one of its members carried out the attack, and police said Tuesday a 23-year-old man has been arrested in South Manchester in connection with the bombing. IS said “a soldier of the caliphate planted bombs in the middle of Crusaders gatherings” then detonated them, though police have only identified an "improvised explosive device" in the attack.

The United States’ top intelligence official says the U.S. government has not yet verified that the Islamic State group is responsible for the Manchester attack. Dan Coats, the director of national intelligence, told Congress that the extremist group frequently claims responsibility for terror attacks.

The attack sparked a nightlong search for loved ones — parents for the children they had accompanied or agreed to pick up, and friends for each other after groups were scattered by the blast. Twitter and Facebook were filled with appeals for the missing.

A police helicopter hummed over the city as somber commuters hurried to work.Public transport shut down, and taxis offered to give stranded people free rides home, while residents opened their homes to provide lodging.

The concert was attended by thousands of young music fans in northern England. Grande, who was not injured, tweeted hours later: “broken. from the bottom of my heart, i am so so sorry. i don’t have words.”

broken. from the bottom of my heart, i am so so sorry. i don't have words.

TMZ is reporting that the 23-year-old singer has suspended the remaining stops on her European tour. Grande was scheduled to perform in London on Thursday.

Police say they know the identity of the bomber but have not provided details yet.

A school in northern England has identified one of the victims in the Manchester concert bombing as Georgina Callander, a former pupil who is now 18, according to BBC.

Peter Rawlinson, deputy of the Bishop Rawstorne Church of England Academy in Croston, northwest of Manchester, told The Associated Press that the school confirmed Callander’s death with members of her family. Rawlinson says “she was academically a very gifted student, very hard-working. Just lovely to speak to.”

The school posted a photo of Georgina on its website, smiling and looking smart in her school uniform. It said she died of injuries from the attack and described her as “a lovely young student who was very popular with her peers and the staff.”

Hayley Lunt was staying at a hotel nearby and had taken her 10-year-old daughter Abigail to her first concert at Manchester Arena on Monday evening.

She said the explosions rang out as soon as Grande left the stage. “It was almost like they waited for her to go.”

“We just ran as fast as we could to get away from that area,” Lunt said. “What should have been a superb evening is now just horrible.”

Campaigning for Britain’s June 8 election was suspended.

The explosion struck near the exit around 10:30 p.m. Monday as Grande was ending the concert, part of her Dangerous Woman Tour. Police cars, bomb-disposal units and 60 ambulances raced to the scene as the scale of the carnage became clear. More than 400 officers were deployed.

“A huge bomb-like bang went off that hugely panicked everyone and we were all trying to flee the arena,” said 22-year-old concertgoer Majid Khan. “It was one bang and essentially everyone from the other side of the arena where the bang was heard from suddenly came running towards us as they were trying to exit.”

Home Secretary Amber Rudd decried “a barbaric attack, deliberately targeting some of the most vulnerable in our society — young people and children out at a pop concert.”The local ambulance service said 59 people were taken to hospitals.

There will be a controlled explosion in Cathedral gardens shortly if you hearing anything don't be concerned.

The city’s regional government and its mayor, Andy Burnham, were among scores of Twitter users who circulated the MissinginManchester hashtag, used by people looking for family members and friends.

Among the names being circulated was Olivia Campbell. Her mother, Charlotte Campbell, said the 15-year-old attended the concert with her best friend from school. He is hospitalized but Olivia is missing, the mother told ITV television’s Good Morning Britain breakfast show.

“I’ve called the hospitals. I’ve called all the places, the hotels where people said that children have been taken and I’ve called the police.”

She said she last heard from her daughter just before the concert.

“If anyone sees Olivia, lend her your phone, she knows my number.”

There was no immediate claim of responsibility. Supporters of the extremist Islamic State group, which holds territory in Iraq’s Mosul and around its de facto capital in the Syrian city of Raqqa, celebrated the blast online.

U.S. President Donald Trump, in Bethlehem, said the attack preyed upon children and described those responsible as “evil losers.”

“This wicked ideology must be obliterated. And I mean completely obliterated,” he added.

Harun Khan, the secretary general of the Muslim Council of Britain, has joined the condemnations of the Manchester attack.

In a statement, Khan says: "This is horrific, this is criminal. May the perpetrators face the full weight of justice both in this life and the next."

British Prime Minister Theresa May says police and security staff in Manchester believe they know identity of the apparent suicide bomber who attacked people leaving an Ariana Grande concert Monday night, but they are not revealing the name for the time being.

Speaking in London, May said: "This attack stands out for its appalling, sickening cowardice."

If the explosion is confirmed as a terrorist attack it would be the deadliest in Britain since four suicide bombers killed 52 London commuters on three subway trains and a bus in July 2005.

Video from inside the arena showed concertgoers screaming as they made their way out amid a sea of pink balloons.

Queen Elizabeth II has expressed her “deepest sympathy” to all those affected by Monday’s bomb attack at a Manchester pop concert, where 22 people were killed.In a statement issued Tuesday, the monarch said “the whole nation has been shocked by the death and injury”.

The Dangerous Woman tour is the third concert tour by 23-year-old Grande and supports her third studio album, “Dangerous Woman.”

Grande’s role as Cat Valentine on Nickelodeon’s high school sitcom “Victorious” propelled her to teen idol status, starting in 2010.

Police responded to reports of an incident at Manchester Arena. Please stay away from the area. More details to follow....

Pop concerts and nightclubs have been a terrorism target before. Most of the 89 dead in the November 2015 attacks in Paris were at the Bataclan concert hall, which gunman struck during a performance by Eagles of Death Metal.

In Turkey, 39 people died when a gunman attacked New Year’s revelers at the Reina nightclub in Istanbul.

Manchester, 160 miles (260 kilometers) northwest of London, was hit by a huge Irish Republican Army bomb in 1996 that leveled a swath of the city center. More than 200 people were injured, though no one was killed.

Gregory Katz reported from London. AP writer Leanne Italie in New York; AP Music Writer Mesfin Fekadu in Jersey City, New Jersey, and Lori Hinnant and John Leiceister in Paris contributed.